International Association
for Cryptologic Research

In 2014, Xu et al. proposed a two-factor mutual authentication and

key agreement scheme for telecare medicine information system (TIMS)

based on elliptic curve cryptography (ECC). However, it has been

shown that Xu et al.\'s scheme is not suitable for practical use as

it is many problems. As a remedy, an improved scheme is proposed

with better security and functionality attributes.